1. Field of the Invention
The present invention relates to an unbalance detecting device and method of a drum washing machine having a 3-phase induction motor operated by an inverter circuit, and more particularly to an unbalance detecting device and method of a washing machine by detecting input voltage variations as well as variations of current ripple thereby providing a more accurate detection of unbalanced mass.
2. Description of the Prior Art
Generally, a drum washing machine includes, as illustrated in FIG. 1, a body 1, a detergent can 3, a manipulating unit 5, both disposed on front upper side of the body 1, and hot and cold water supply valves 7 and 8 connected to a faucet (not shown) for supplying hot and cold water.
The body 1 is in turn disposed with a tub 9 in which there is arranged with a rotatory drum for washing and spin-drying the laundry. The tub 9 is provided at a front side thereof with a diaphragm 15 for coupling a door 13 for opening and closing when the laundry is tossed in or taken out. The tub 9 is disposed at a front side thereof with a balance weight 19 for preventing vibration generated from a high speed rotation of the drum 11 during washing and spin-dry operations.
The diaphragm 15 is disposed thereon with an air vent 17 for inducing dry air during drying operation of the laundry. The air vent 17 is arranged therein with a drying heater 21 for drying air induced from outside.
The drying heater 21 is formed at one side thereof with a fan motor 23 for blowing high-temperature air provided by the drying heater 21 to the drum 11 via the diaphragm 15.
The tub 9 is connected at a periphery thereof to a condensing hose 25 for supplying cold water to condense the dried air infused into the tub from the drying heater 21, and the tub 9 is provided thereunder with rotation force generating means of 3-phase induction motor 27 (hereinafter referred to as motor) for rotating the drum 11 in the forward and reverse directions.
The body 1 is mounted at a rear lower side thereof with a drainage pump 29 for draining the washing water in the tub 9 through a drainage hose (not shown) and at a front lower side thereof with a filter 31 for preventing the drainage pump 29 from being clogged by residual water, filth and the like flowed out from the tub 9 and for draining the washing water in case the drainage pump 29 could not operate due to, such as blackout.
The drum 11 is formed at overall surfaces thereof with a plurality of through holes 11a for allowing the washing water in the tub 9 to flow into the drum 11. The drum 11 is provided therein with a water flowage adjusting member 11b performing as a laundry paddle for allowing the laundry to tumble in the drum 11 and pulling up and dropping the laundry. Each of the water flowage adjusting members is spaced 120.degree. apart from one another.
In the conventional drum washing machine thus described, when a user inserts the laundry (clothes) into the drum, manipulates the manipulating unit 5 to input a desired washing condition (according to the kind of laundry, temperature, washing course, dry time and the like) and presses an operation button, washing water is supplied into the tub 9 from a faucet (not shown) through the hot and cold water valves 7 and 8.
When the washing water is supplied into the tub 9, the drum 11 is rotated at a high speed in forward and reverse directions according to the operation of the motor 27 in order to form water flowage in the supplied washing water and to apply physical force to the laundry, thereby separating grime, foreign objects and the like stained on the laundry, and then the laundry passes through the washing, rinsing and drying processes.
Ripple width of electrical current supplied to the motor 27 during the spin-dry operation is proportional to unbalanced mass generated by eccentricity of laundry when the drum rotates at a high speed, such that the ripple width of the current is detected by a current sensor, and the detected ripple width of current is compared with a size of a predetermined ripple width. Then, if the detected rippled width of the current is larger than the predetermined value, the spin-dry operation is stopped or changed to the fabric unravelling operation.
However, according to the conventional method, since only the rippled width of current generated by the unbalanced mass could be detected, when an abnormal voltage, which is lower (.about.195 volts) or higher (250 volts.about.) than the normal voltage, is applied, data from the ripple width of current are overlapped so as to make it difficult to detect accurate unbalance.